New $ubvri$ photometry of 234 M33 star clusters

TL;DR

This study provides new UBVRI photometry for 234 M33 star clusters, enhancing existing data and revealing insights into their ages and masses, with implications for understanding galaxy star formation history.

Contribution

It offers the second set of UBVRI photometry for M33 clusters, significantly increasing data coverage and enabling detailed age and mass analysis.

Findings

Most clusters lack multi-band photometry in previous studies.

Young clusters ($ extasciitilde 10^7$ yr) have masses below $10^5$ $M_{igodot}$.

Clusters exhibit a wide age range, some comparable to Galactic globular clusters.

Abstract

This is the second paper of our series. In this paper, we present $UBVRI$ photometry for 234 star clusters in the field of M33. For most of these star clusters, there is photometry in only two bands in previous studies. The photometry of these star clusters is performed using archival images from the Local Group Galaxies Survey, which covers 0.8 deg$^2$ along the major axis of M33. Detailed comparisons show that, in general, our photometry is consistent with previous measurements, especially, our photometry is in good agreement with Zloczewski & Kaluzny. Combined with the star clusters' photometry in previous studies, we present some results: none of the M33 youngest clusters ($\sim 10^7$ yr) have masses approaching $10^5$ $M_{\odot}$; comparisons with models of simple stellar populations suggest a large range of ages of M33 star clusters, and some as old as the Galactic globular clusters.